body,html {
  width: 100%;
  height: 100%;
  overflow: hidden;
  padding: 0;
  margin: 0;
  max-width: 600px;
}

body {
  padding: 10px;
  transition: all 1s;
}
div.pic img {
  width: 100%;
}

#modeBtn {
  border: 0;
  background: transparent;
  font-size: 36px;
  float: right;
  cursor: pointer;
}

body.night {
  background: #000;
  color: white;
}